This invention relates generally to electrical blade fuses, and to housings for use in blade fuses, for either high or low voltage applications.
Electrical blade fuses are well-known in the art. The modern electrical blade fuse was perfected by Littelfuse, Inc., the assignee of the present invention, and was described in many patents owned by the assignee. These patents include, but are not limited to, Littelfuse""s U.S. Pat. Nos. 3,909,767; 4,023,365; 4,131,869; 4,580,124; 4,604,602; 4,635,023; 4,661,793; 4,997,393; 5,139,443; 5,663,861; and 5,668,521.
Some of fuses described in these patents include either a V-shaped or a sinusoidal-shaped fuse link. One example of such a V-shaped fuse link is that shown in U.S. Pat. No. 4,131,869. The V-shaped fuse link is shown as item 20 in FIG. 13 of the ""869 patent, and is described at column 6, line 56, through column 7, line 18 of the ""869 patent.
As is well-known in the art, blade fuses of the types shown in the above-referenced patents protect electrical circuits from current overloads. This protection results from the creation of a short in the fuse, and therefore in the circuit protected by the fuse, upon certain current overload conditions. Particularly, the fuse link breaks or opens upon current overload during a predetermined length of time.
Many of these blade fuses are extensively used in automobiles, and are therefore designed to be rated for service up to 32 volts. Now, however, automobile manufacturers are designing more electrical accessories into automobiles, and are also designing or contemplating vehicles that use electrical motors, rather than internal combustion engines, for propulsion. Both of these developments increase the electrical demands upon current and future vehicles. As a result, circuits rated at 60 volts and higher are now being contemplated for automobiles.
When the fusible link opens in fuses like those of the ""869 patent, especially those rated at up to 32 volts, an arc forms between the melted ends of the fusible link. At these lower voltages, the arc will not cause serious damage to the metal and plastic portions of the fuse. Even at these lower voltages, however, an arc can cause some discoloration or disfiguration of the fuse components. At higher voltages, moreover, significantly more extensive damage to the metal and plastic portions of the fuse can occur.
The invention is a housing for a blade fuse. The housing includes a first generally planar wall and a second generally planar wall. Each of these two planar walls has an outer surface and an inner surface. The inner surface of the first generally planar wall faces the inner surface of the second generally planar wall.
Each of the generally planar walls have a pair of ribs extending from those inner surfaces. The ribs act as arc barriers. The two ribs on the inner surface of the first generally planar wall extend towards, and are generally aligned with, the two ribs on the inner surface of the second generally planar wall. While the ribs on the inner surfaces of the first and second generally planar walls extend towards each other, they do not touch, but instead form a gap. The gap is sized so as to permit the insertion of a fuse element that is a component of the completed blade fuse. Preferably, this gap is sized so that upon manual or automated insertion of the fuse element, no portion of its fusible link will contact any of the adjacent ribs. Such contact could cause distortion of the fusible link, and such distortion could damage the assembled fuse.
One aspect of the invention is a blade fuse where the ribs are integrally formed with the blade fuse housing.
In yet another aspect of the invention, the ribs have a height in excess of one-half of the height of the blade fuse housing.
Another aspect of the invention is a blade fuse, combining a metallic, fuse element, and the housing of the invention. The blade fuse and the blade fuse housing of the present invention are suitable for use in a circuit having a voltage rating of sixty volts and higher.